Submitted to: Helia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 3, 1997
Publication Date: N/A
Interpretive Summary: Two moth species, the banded sunflower moth and the sunflower moth are pests of cultivated sunflower. The life styles of both moth species are similar. The immature stages of both moths feed on the flower parts and the seeds of the sunflower head. Experiments have been conducted with the sunflower moth that indicated some floral parts of the sunflower head contained materials that caused the immature stages of the moth to die before reaching maturity. Evidence that such materials are present in a crop plant may be useful in developing control procedures for pest insects. Therefore, it seemed instructive to see if the same floral parts or another part of the sunflower caused death of the immature stages of the banded sunflower moth. It was found that sunflower seed contained a chemical component that increased mortality of banded sunflower moths. Floral parts did not have the deleterious effect on the banded sunflower moth that was seen with the sunflower moth. The differences in response of two competing insect species probably reflected distinct adaptations to their cultivated sunflower host. Since sunflower seed contained materials with harmful effects on the banded sunflower moth, selection of sunflower plants that produced seed with increased activity against the banded sunflower moth could be useful for developing greater control of this pest insect.
Technical Abstract: Hybrid sunflower florets have been reported to express insect resistance in the form of larvicidal effects when floret extracts were incorporated into the diet of the larvae of laboratory reared moths, Homeosoma electellum (Hulst). This study was undertaken to determine if hybrid sunflower florets, seed, ray flowers or leaves had developmental or larvicidal effects on larvae of the banded sunflower moth Cochylis hospes Walsingham. Larval mortality decreased significantly relative to the rearing diet when larvae were fed a diet prepared with acetone extracted seed and increased again when the acetone extractable were added back into the diet. Sunflower florets significantly increased survival of C. hospes larvae, relative to the rearing diet. Incorporation of florets, ray flowers, or leaves into the diet significantly increased or left unchanged the time to develop from the beginning of the first instar to the pupal stage. The results may reflect adaptations of distinct insect species to the components and parts of their cultivated sunflower host. Selection of sunflower seed for increased activity could be useful for greater control of this pest insect.